shecky

True. But not many bikes made with it. Most welded steel frames I've come across are chromoly. Or plain ole' "high tensile" steel. I don't know how many welded steel frames are heat treated. Anecdotally, on generally abused bikes, I've noticed frame failures tend to develop around welds. I've not known many lugged frames to get similar abuse.

As already said, it really doesn't matter a whole lot. Lugs, welds, fillet brazing have all proven to be quite durable enough for bike frames.

Brazed joints are quite resistant to "pulling out". Which is the comparison to welding. There may or may not be more surface area bonded between lugged joints, and brazing material in such tight joints have very high resistance to shear stresses.

Seems to me the bending strength of lugged joints may be mostly a result of the strength of the actual lugs, not necessarily the joining method. The area of tube/lug overlap are probably quite strong. However, tubes can only extend so far and it seems ultimately the weak point would be the lug (if it can be considered weak at all).

I have wondered about the strength of cast lugs. I wonder if lugs are (were) sometimes made differently. Perhaps formed from sheet or tubing.